Unsilent Night is Phil Kline's free outdoor participatory sound sculpture of many individual parts, recorded on cassettes, CD's and mp3's, and played through a roving swarm of boomboxes carried through city streets every December. People bring their own boomboxes and drift peacefully through a cloud of sound which is different from every listener's perspective. Kline says: "In effect, we become a city-block-long stereo system."

Since its debut in 1992, Unsilent Night has become a cult holiday tradition in NY, drawing crowds of up to 1,500 participants. Unsilent Night 2009 took place in more than 25 cities around the world and for the first time in London, Berlin, Denver, and Dallas.